Patent Literature 1 discloses that air-conducted sound and bone-conducted sound are known examples of sound transmitted to a human being from a device such as a mobile phone. As the air-conducted sound, Patent Literature 1 discloses a sound that is transmitted to the user's auditory nerve by air vibrations, caused by a vibrating object, that are transmitted through the external ear canal to the eardrum and cause the eardrum to vibrate. As bone-conducted sound, Patent Literature 1 discloses a sound that is transmitted to the user's auditory nerve through a portion of the user's body (such as the cartilage of the outer ear) that is contacting a vibrating object.
Patent Literature 1 also discloses a telephone that transmits sound to a user by air-conducted sound and bone-conducted sound, in which a rectangular vibrating body, formed from a piezoelectric bimorph and a flexible substance, is attached to an outer surface of a housing via an elastic member. When voltage is applied to the piezoelectric bimorph of the vibrating body, the piezoelectric bimorph expands and contracts in the longitudinal direction, thereby causing the vibrating body to vibrate. Patent Literature 1 also discloses that air-conducted sound and bone-conducted sound are transmitted to the user when the user contacts the vibrating body to the auricle.
Patent Literature 2 discloses joining a piezoelectric element near an edge in the lengthwise direction of a mainly rectangular panel and vibrating the panel by driving the piezoelectric element.